The present invention relates to control modules for motor vehicle cabs.
More particularly, the invention relates to a control module associating an electronics card for controlling various functions on a vehicle with a power card for protecting controlled circuits, and for relaying and distributing power.
The main technological difficulty encountered with control modules of this type lies in providing mechanical and electronic coupling between the power card and the control card.
A power card is a printed circuit designed to protect circuits that switch currents that may be as high as 40 amps or more. They carry protection devices such as fuses and relays, and their substrates and layers of copper need to be thick. The overall thickness of such a copper layer is generally about 200 microns (xcexcm) to 400 xcexcm.
A control card carrying control electronics, need only have a substrate that is thin. For example it may be constituted by a single- or double-sided printed circuit with one or two layers of copper that are about 35 xcexcm thick.
The power card and the control card thus correspond to different manufacturing and connection technologies.
As a result, the two cards, i.e. the power card and the control card, are difficult to connect together.
This difficulty is made worse by the fact that the power card needs to have tracks that are wide so it is not possible to bring its connection points together in a single location since it turns out to be impossible to lay out the tracks of the power card in that way.
DE 40 37 803, and also the article xe2x80x9cElectronic high density packaging for under the hoodxe2x80x9d, Automotive Engineering, Vol. 100, No. 3, March 1st, 1992, pp. 13-15, both disclose control modules comprising a single box containing a power card and a control card.
However the control modules described in those two documents do not enable power components to be inserted without opening the box.
Each of the boxes is made up of a plurality of separate parts and consequently requires a plurality of manufacturing molds.
In addition, the structures described in DE 40 37 603 in which an electronics card is disposed perpendicularly to a power card are of considerable bulk and do not provide satisfactory mechanical protection to the electronics card.
The object of the present invention is to solve the problem posed by interconnecting the two portions by means of a solution that is simple, low cost, and appropriate.
The invention provides a control module for a motor vehicle cab, the module comprising a box, at least one power card and at least one control card placed in said box, wherein the control card extends substantially perpendicularly to the power card and wherein said box is constituted by two half-boxes that are closed together and hinged about a hinge with which they are integrally formed, one of the half-boxes having means forming housings that receive tongues and/or female pins which co-operate with said housing-forming means to define connectors, and also having a case which provides mechanical protection for the control card.
Said module is advantageously associated with the following various characteristics taken singly or in any technically feasible combination:
the control card has a plurality of tracks which extend beyond said card, said tracks being carried on said card by zones that are separated by notches, and the power card has a plurality of slots in which said zones carrying said tracks are designed to extend, said power card itself having tracks at said slots to which the tracks of the control card are connected;
the power card comprises a plurality of superposed single-sided printed circuits;
the power card comprises a flexible printed circuit; and
the half-box which includes housing-forming means which receive tongues and/or female pins, and also a case which provides mechanical protection for the control card, also carries at least one housing for a component that is soldered directly to the power card.
The invention also provides a method of making such a module, the method including the various following steps:
the control card, the tongues, and the female pins are inserted in the housings corresponding thereto in one of the half-boxes;
thereafter, the power card is put in place on the ends of said tongues and pins and on the control card;
any optional power components are positioned on said half-box and the power card;
flow soldering is then performed on the face of the card through which there project the ends of the tongues, the pins, and any power components of the relay type; and
the two half-boxes are closed together.
The invention also provides a box for a control module of the above-specified type, the box being constituted by two half-boxes that are closed together and hinged about a hinge integrally formed therewith, one of the half-boxes including housing-forming means for receiving tongues and/or female pins which co-operate with said housing-forming means to define connectors, and also a case for providing mechanical protection to the control card.